**Abstract**

Pests are highly responsible for heavy crop losses and reduced food supplies, poorer quality of agricultural products, economic hardship for growers and processor. Generally, chemical control methods are practiced for their control which is neither always economical nor effective and may have associated unwanted health, safety and environmental risks. However, to meet the challenge of feeding to the ever increasing human population, an efficient, economical and environment friendly disease control methods are requisites. In this regard, biological control may be an effective means of reducing or mitigating the pests and pest effects through the use of natural enemies. Biological control is an environmentally sound which involves the use of beneficial microorganism to control plant pathogens and diseases they cause. Therefore, in this chapter we will provide a comprehensive account of this environmental friendly approach for effectively management of plant diseases. This chapter will also accentuate the development of biological control agents for practical applications and the underlying mechanism. The contents in the chapter will be beneficial and advantageous to all those working in academia or industry related to crop protection.

**Keywords:** bioinsecticides, biological control, crop protection, insecticides, pests
